<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Form
 * @subpackage Decorator
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */

/** Zend_Form_Decorator_Abstract */
require_once 'Zend/Form/Decorator/Abstract.php';

/**
 * Zend_Form_Decorator_Callback
 *
 * Execute an arbitrary callback to decorate an element. Callbacks should take
 * three arguments, $content, $element, and $options:
 *
 * function mycallback($content, $element, array $options)
 * {
 * }
 *
 * and should return a string. ($options are whatever options were provided to
 * the decorator.)
 *
 * To specify a callback, pass a valid callback as the 'callback' option.
 *
 * Callback results will be either appended, prepended, or replace the provided
 * content. To replace the content, specify a placement of boolean false;
 * defaults to append content.
 *
 * @category   Zend
 * @package    Zend_Form
 * @subpackage Decorator
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id: Callback.php 18951 2009-11-12 16:26:19Z alexander $
 */
class Zend_Form_Decorator_Callback extends Zend_Form_Decorator_Abstract
{
	/**
	 * Callback
	 * @var string|array
	 */
	protected $_callback;

	/**
	 * Set callback
	 *
	 * @param  callback $callback
	 * @return Zend_Form_Decorator_Callback
	 * @throws Zend_Form_Exception
	 */
	public function setCallback($callback)
	{
		if (!is_callable($callback)) {
			require_once 'Zend/Form/Exception.php';
			throw new Zend_Form_Exception('Invalid callback provided to callback decorator');
		}
		$this->_callback = $callback;
		return $this;
	}

	/**
	 * Get registered callback
	 *
	 * If not previously registered, checks to see if it exists in registered
	 * options.
	 *
	 * @return null|string|array
	 */
	public function getCallback()
	{
		if (null === $this->_callback) {
			if (null !== ($callback = $this->getOption('callback'))) {
				$this->setCallback($callback);
				$this->removeOption('callback');
			}
		}

		return $this->_callback;
	}

	/**
	 * Render
	 *
	 * If no callback registered, returns callback. Otherwise, gets return
	 * value of callback and either appends, prepends, or replaces passed in
	 * content.
	 *
	 * @param  string $content
	 * @return string
	 */
	public function render($content)
	{
		$callback = $this->getCallback();
		if (null === $callback) {
			return $content;
		}

		$placement = $this->getPlacement();
		$separator = $this->getSeparator();

		$response = call_user_func($callback, $content, $this->getElement(), $this->getOptions());

		switch ($placement) {
			case self::APPEND:
				return $content . $separator . $response;
			case self::PREPEND:
				return $response . $separator . $content;
			default:
				// replace content
				return $response;
		}
	}
}
